#12696: Exception gives not enough information to be useful -------------------------------------+------------------------------------- Reporter: flip101 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: exception Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by flip101): Maybe a test case is not needed to help the issue along .. i discovered some more things {{{ λ> :trace main Stopped in <exception thrown>, <unknown> _exception :: e = _ λ> :print _exception _exception = (_t1::e) λ> seq _exception () () λ> :p _exception _exception = GHC.Exception.SomeException (GHC.Exception.ErrorCallWithLocation (_t9::String) (_t10::String)) λ> _t9 "Data.Data.fromConstr" λ> _t10 "" }}} https://hackage.haskell.org/package/base-4.9.0.0/docs/src/Data.Data.html#fro... I would say this pretty much points to the origin of the exception. I found out about the seq-trick after another read of the debugging wiki. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12696#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler